The present invention relates generally to a mechanical punch for punching holes in paper-based materials and, more particularly, to a mechanical punch for punching dried blood spots from dried blood spot test cards.
To detect the presence of viral and bacterial infections and diseases in individuals, such as HIV-1, disease-specific blood test kits have been devised for at-home or doctor-office use. The test kit typically includes a test card, formed of filter paper or other suitable material, having designated areas for depositing one or more drops or samples of the individual's blood. After the individual places the blood samples on the test card, the samples dry and the test card is delivered to a laboratory for testing.
To test the individual's blood for the specific infection or disease in question, at least one dried blood spot (DBS) must first be removed from each blood sample on the test card. Conventionally, mechanical punches have been used to remove the DBSs from the test card.
Typically, these mechanical punches have been designed to remove a DBS of a specific size from a blood sample on a test card. For example, conventional punches have been designed to remove a DBS of 1/4" in diameter from a blood sample that may range from 1/2" to 5/8" in diameter. Two such punch devices are manufactured by I.E.M. of North Hollywood, Calif., and BSD Technologies International of Austria, respectively.
One disadvantage of this type of punch is that the diameter of the removed DBS cannot be varied to accommodate for differing sizes of blood samples. Consequently, because the number and amount of blood samples are limited and it is normally desirable to obtain as many DBSs from each blood sample as possible to insure accurate testing, the size of the punch may not be adjusted to provide the most efficient sizing and removal of DBSs.
In addition, many conventional punch devices cut the paper in a tearing or "scissor" motion in which the leading edge of a cutting pin initially contacts the paper and then progresses in a radial motion through the paper to complete the cut. This "tearing" action detrimentally affects the precision of the cuts made by the punches.